BlockSec DeFi攻击分析系列之二倾囊相送:Sushiswap手续费被盗-ODAILY_QUO:SWAP

去中心化金融(DeFi)作为区块链生态当红项目形态,其安全尤为重要。从去年至今,发生了几十起安全事件

BlockSec作为长期关注DeFi安全的研究团队(https://blocksecteam

_toWETH函数:

function_toWETH(addresstoken)internalreturns(uint256){//对于SUSHI,直接Sushimaker全部SUSHI转给Barif(token==sushi){uintamount=IERC20(token)

//对于WETH,直接将全部WETH转给WETH/SUSHI交易对,swap出相应的SUSHIif(token==weth){uintamount=IERC20(token)

//获取token/WETH的交易对地址IUniswapV2Pairpair=IUniswapV2Pair(factory

//计算可以换出的WETH数量:amount0out,amount1Out//获得交易对中两种资产的数量(uintreserve0,uintreserve1,)=pair

看出什么亮点了吗?

SushiMaker里的转账逻辑都是:transfer(balanceOf(this))

我们可以分两个阶段来看convert的调用过程:第一个阶段:在convert函数中SushiMaker拥有的是SLP,它通过burnbalanceOf(this)实现将全部SLP换成两个底层代币第二个阶段:SushiMaker获得了burn来的底层代币,再拿burn得到的token去不同的交易池换wETH

你发现哪里有问题了吗?我们来看第二阶段的代码_toWETH:注意兑换的逻辑为:

uintamount=IERC20(token)

,"profit":"0

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俄勒冈州金融监管部将从BlockFi获得近100万美元和解金:7月1日消息,作为加密货币金融机构 BlockFi 与美国多州和解协议的一部分,俄勒冈州金融监管部将从 BlockFi 获得近 100 万美元赔偿。此前,俄勒冈州金融监管部对 BlockFi 违反俄勒冈州证券法提起了法律诉讼,声称 BlockFi 在未经适当注册的情况下在俄勒冈州提供和出售证券此外,BlockFi 向公众提供利息账户(BIA),通过利息账户,投资者可以将比特币和以太坊等加密货币存入,然后将加密资产借给 BlockFi,以换取该公司承诺提供可变的每月利息支付,BlockFi 承诺的月利率为 6.2%,根据投资的类型和规模,每个月的复合利率最高可达 9.5%。

作为与证券监管机构和解的一部分,BlockFi 同意支付总计约 1 亿美元的和解金,其中一半将支付给美国证券交易委员会,另一半支付给各州证券监管机构。BlockFi 将停止向俄勒冈州的新投资者提供利息账户或出售任何未注册、合格或豁免的证券,并向俄勒冈州金融监管部支付 943,396 美元。(KTVZ)[2022/7/1 1:44:22]

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动态 | 泰国Block chainstore旗下ECOC主网将于10月28日上线:据泰国Block chainstore官方消息,其旗下ECOC主网将于2019年10月28日正式上线。据介绍,ECOC采用POS共识,侧重区块链共识底层技术安全及TPS交易速度(560/M),同步可扩展智能合约跨链功能。[2019/10/21]

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动态 | BM 透露 Block.one 也会开发 Android 钱包:据 IMEOS 报道,继此前 BM 提到 Block.one 会开发 EOS 的 IOS 钱包后,在回答社区成员提问时, BM 刚刚透露Android EOS 钱包也会开发。[2018/8/10]

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蚂蚁技术实验室发布全球首款区块链喷漆Block 7:蚂蚁技术实验室发布全球首款区块链喷漆Block 7,据悉将这款漆喷在车上,就能将汽车变成区块链上的节点。遇上车辆事故,汽车上的各种传感器会自动将本车车体形变、行人间距、视频记录做好数据安全转换后上链,同时请求附近上链的汽车、智能路灯、摄像头等交通设施联合作证,通过多方交叉验证,迅速还原真实现场。[2018/4/2]

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Blockstream新推出闪电网络应用程序解决闪电支付的小费问题:Blockstream发布公告宣布推出新应用Nanotip LApp。Nanipip LApp通过创建一个简单的Web服务器,即时编写闪电支付请求,解决了闪电支付小费支付的请求问题。它为每个内容提供商提供了他们自己的的支付机器人(tip-bot),但是这样做的方式可以让这些创作者完全控制消费致富,同时赋予他们比传统比特币支付小费更强的隐私。这是Blockstream推出的第三款闪电网络应用程序。[2018/3/27]

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后续攻击者又尝试攻击Sushiswap的其他相关仿盘项目,如LuaSwap:

https://etherscan

function_toETH(addresstoken){..

New:0x280ac711bb99dE7C73FB70fb6DE29846D5e4207Ffunctionconvert(addresstoken0,addresstoken1)public{//Atleastwetrytomakefront-runninghardertodo

function_toETH(addresstoken,uintamountIn){...}

可以看到区别在于:代码第26行_toWETH限制了amount,这样修改以后就不会将SushiMaker中存的全部SLP都去池中换成wETH,而只是换取burn出的一部分

但是这样问题就解决了吗?其实还没有,时隔两个月,同样的地方,Sushiswap又中了见:amenda:SushiSwap攻击事件(2021年1月27号)分析(https://zhuanlan.zhihu.com/p/372058217)

0x3.参考

以小博大,简述SushiSwap攻击事件始末:https://www.chainnews.com/zh-hant/articles/726256718885.htm

Astokenpricerisesandreputationmends,Sushiswapfoilsmidnightexploit:https://cointelegraph.com/news/as-token-price-rises-and-reputation-mends-sushiswap-foils-midnight-exploit

AnevolutionofUniswapwithSUSHItokenomics:https://sushichef.medium.com/the-sushiswap-project-dd6eb80c6ba2

一文看懂Uniswap和Sushiswap:https://zhuanlan.zhihu.com/p/226085593

sokdecentralizedexchanges(dex)withautomatedmarketmaker(amm)protocols:https://arxiv.org/abs/2103.12732

AttackingtheDeFiEcosystemwithFlashLoansforFunandProfit:https://arxiv.org/abs/2003.03810

https://www.blocksecteam.com/

contact@blocksecteam.com

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金宝趣谈

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